Evgeny Lisakonov: “In terms of the degree of purification, our waste water is close to drinking water. Modernization of biological wastewater treatment facilities has been completed in Lipetsk
The city of Lipetsk is a regional center with a population of 511 thousand people, located on both banks of the Voronezh River. Lipetsk is a modern, well-maintained city with a centralized water supply and sewerage system.
The treatment facilities are located on the Left Bank of the Voronezh River. The first complex of mechanical wastewater treatment facilities with a capacity of about 80 thousand cubic meters per day was launched in 1967.
The first set of biological treatment facilities was put into operation in 1975. The wastewater treatment plant of the Novolipetsk Metallurgical Plant, established in 1977, was reconstructed and operated until 2007.
In October 2007, on the initiative of the Administration of the city of Lipetsk, under the jurisdiction of the Department of Housing and Communal Services, the municipal unitary enterprise “Lipetsk Aeration Station” was formed, or as it is called briefly - MUP “LiSA”. It includes two technological lines, into which a single complex of treatment facilities is conventionally divided.
The first line, reconstructed in 2006, with a design capacity of 90 thousand cubic meters per day for wastewater from the left bank of the city, remained the property of the Novolipetsk Metallurgical Plant and was transferred to the municipal unitary enterprise "LiSA" on the basis of a service agreement. The second technological line has an actual capacity of 150 thousand cubic meters per day and purifies wastewater from the right bank part of the city. NLMK transferred it to municipal ownership free of charge, and now it is operated by the municipal unitary enterprise LiSA under the right of economic management.
The technological scheme of communications allows you to redistribute water flows between lines if necessary. For example, during repairs or reconstruction.
The area occupied by the enterprise is 62 hectares. There is a reinforced concrete fence along the entire perimeter, about 5 km long, and the entire territory is under guard.
MUP "LiSA" does not work directly with the population and carries out wastewater treatment activities under contracts with three large subscribers - with "LGEK", an enterprise that provides water supply and wastewater disposal for the city, the Novolipetsk Metallurgical Plant and the Lipetskkompleks meat processing plant.
For the disposal of liquid household waste from unsewered areas of the city, since 2008, the enterprise has equipped a receiving station for special vehicles, and has organized recording of volumes of reinforced waste.
Treatment facilities are a complex of facilities for mechanical and biological wastewater treatment, disinfection of treated wastewater and sludge treatment. The facilities provide for purification from nitrogen and partially from phosphorus.
Purolate is used at wastewater treatment plants in accordance with the requirements of the Chief Sanitary Doctor of Russia. The drug is introduced into the wastewater into the channels after the screens on both production lines. To ensure its effectiveness, the required amount of the drug is 1 liter per 7000 m 3 /hour of wastewater. Since 2010, its dosing has been switched to automatic mode. Consumption control is organized in such a way that, through the e-government system, all regulatory authorities have access to information on the use of the drug - for example, Rospotrebnadzor in the Lipetsk region and Russia.
After receiving chambers, wastewater enters sand traps designed to clean wastewater from sand, which is removed to sand pads for dewatering. From sand traps, wastewater from the second process line flows into primary settling tanks, where suspended solids settle. They are subsequently removed to sludge treatment facilities. Also in the primary settling tanks, floating impurities are removed, which are discharged to sludge beds for disinfection.
Clarified wastewater after primary settling tanks is supplied to aeration tanks. One of them is a nitri-denitrifier aeration tank, the other three are displacer aeration tanks.
There are no primary settling tanks on the first line in the technological cycle. And the wastewater after the sand traps immediately goes to three aeration tanks of the nitri-denitrifier.
The process of biological treatment in aeration tanks is based on the ability of certain types of microorganisms, under certain conditions, to use pollutants for their nutrition. Many microorganisms (bacteria, protozoa, algae) make up the activated sludge of a biological treatment plant, which, while in wastewater, absorbs pollutants inside the cell, where they undergo biochemical transformations under the influence of enzymes. This ensures the removal of organic contaminants, nitrogen and phosphorus compounds.
According to the project, the time required to complete all processes in wastewater located in the aeration tank is about 16 hours. The entire cleaning process takes place with the participation of air, which enters through aeration porous pipes. Air is supplied to the aeration system from blowers through a duct system with shut-off and control valves.
After the aeration tanks, the sludge mixture goes to secondary settling tanks. They are an integral part of biological treatment facilities and serve to separate activated sludge and biologically purified water. Activated sludge settles to the bottom of the settling tank and is removed into the sludge chamber.
Biologically purified water is sent for disinfection using ultraviolet radiation. The Ural Federal District station of the first line was built by the metallurgical plant and has been in operation since 2006. The construction of the UFO station of the second line cost the city budget 100 million rubles in 2008. This made it possible to completely abandon the use of sodium hypochlorite, as a source of formation of by-products harmful to the reservoir and human health, and also as insufficiently effective against a number of microorganisms.
The disinfecting effect of ultraviolet light is based on irreversible damage to nucleic acids, which are contained in all cells of living organisms and are carriers of hereditary information. After this, the reproduction of microorganisms becomes impossible.
During wastewater treatment, sludge is formed. Its bacterial contamination is high, and it also has poor water yield, since most of the water is in a bound state. Therefore, to reduce the volume of sludge formed and to disinfect it, sludge treatment facilities are used - aerobic stabilizers, sludge compactors, sludge tanks, a mechanical dewatering shop, sludge platforms and sludge storage tanks.
Aerobic stabilizers with an aeration system are designed to improve settling properties. They receive excess activated sludge and raw sediment from primary settling tanks. The mixture of raw sludge and excess activated sludge is aerated with air for 48 hours. The stabilized sludge enters the receiving chamber of sludge compactors, which are designed to compact activated sludge.
Dewatering of compacted sludge is carried out on belt filter presses with thickeners using a flocculant. The dewatered sludge enters the vehicle via a conveyor and is transported to sludge storage tanks or sludge beds on the territory of the enterprise. From storage tanks, sewage sludge is transported to storage sites at a distance of 30 km from the city for disinfection for 5 years. In the future, the sediment will be used as fertilizer in agriculture, landscaping, land reclamation, and in forest nurseries. The enterprise has a certificate from the Ministry of Natural Resources of the Russian Federation on the environmental compliance of the treated sludge with standards.
Wastewater is discharged through three pipelines with a diameter of 1200 mm into the Voronezh River within the city. To achieve the maximum permissible concentration standards of a fishery reservoir in treated wastewater, the administration of the city of Lipetsk is reconstructing the treatment facilities of the second technological line.
In 2010, three primary settling tanks were reconstructed into a nitri-denitrifier aeration tank. This increased the capacity of treatment facilities and the quality of treatment. By 2013, it is planned to reconstruct three primary settling tanks, three aeration tanks, eight secondary settling tanks, an air blowing station, and an activated sludge station using a loan from the European Bank for Reconstruction and Development in the amount of 311 million rubles and the city budget in the amount of 57 million rubles.
The company employs 211 people. The average age of employees is 44 years. 63% of women and 37% of men work in municipal unitary enterprises. The number of working days in a year is 365.
The structure of the enterprise includes technological personnel, mechanical, electrical, transport and repair and construction services, administrative personnel, as well as a production chemical laboratory. It is accredited for technical competence and carries out production control over the quality of wastewater treatment for more than 30 indicators. In addition, studies of activated sludge and sewage sludge are carried out.
River water is examined every 10 days. This is necessary in order to determine what effect discharged wastewater has on the Voronezh River. Samples are taken from the reservoir before and after treatment facilities. The analysis results show that the quality of wastewater treatment is such that its discharge does not significantly change the properties of water in the river.
To preserve the life and health of workers, the necessary working conditions have been created, people are provided with special clothing, special food, and protective equipment. There is a health complex for the company’s employees in the administrative building. A number of social programs for employees are being implemented. According to the terms of the Collective Agreement, funds are allocated for the health improvement of workers and the recreation of their children in sanatoriums, rest homes, boarding houses, and children's health camps. In 2011, MUP "LiSA" took second place in the regional competition of collective agreements.
COMPANY BOOKLETS
In Lipetsk, the next stage of reconstruction of the city aeration station has been completed - modernization of biological wastewater treatment facilities. Within this stage of the project with a total cost of 368 million rubles. Three aeration tanks, six secondary settling tanks were reconstructed and a new blower station was built. This made it possible to increase the capacity of structures from 170 thousand m3/day. up to 221 thousand m3/day. and ensure the standard level of wastewater treatment.
In the next two to three years, it is planned to reconstruct the sludge treatment and disposal facilities, the cost of which is estimated at 250 million rubles.
Sergey Linev, director of the Lipetsk Aeration Station municipal unitary enterprise, talks about this.
MUP Lipetsk Aeration Station (MUP LiSA) carries out mechanical and biological treatment of wastewater that enters through the centralized sewerage system of Lipetsk with a population of more than 500 thousand people. In 1975, in the city of Lipetsk, a complex of mechanical and biological wastewater treatment facilities was put into operation, designed to treat 170 thousand m3/day. Due to the development of industry and an increase in the urban population, the hydraulic load has increased, as well as the concentration of pollutants in the incoming wastewater. For these reasons, the requirements for the quality of treated wastewater into the Voronezh River at the level of the maximum permissible concentration of a fishery reservoir could not be achieved at existing biological treatment facilities without the introduction of new technologies, including for the removal of nutrients (nitrogen and phosphorus compounds).
As part of the target program, it was decided to stage-by-stage reconstruct the city's treatment facilities due to the large volume of activities being implemented and the impossibility of suspending the operation of treatment facilities.
The total cost of the reconstruction project is 368 million rubles. The European Bank for Reconstruction and Development provided MUP "LiSA" with a long-term loan in the amount of 311 million rubles. Co-financing from the city amounts to 57 million rubles.
At the first stage in 2008-2009. The construction of a UV disinfection station was carried out. The equipment was supplied by NPO LIT (Moscow) of tray type 88MLV-36A. Panel gates for the Ural Federal District were supplied by NPF Ecoton CJSC (Belgorod). The cost of the project was 100 million rubles, financing was provided from the city budget.
As part of the second stage of reconstruction of treatment facilities, in 2010, three primary settling tanks were reconstructed into a nitride-denitrifier aeration tank. The following equipment was introduced:
— tubular aerators of JSC NPF “Ekoton” with a diameter of 120 mm;
— two FLYGT (Sweden) series 3001 pumps with a capacity of 1500 m3/hour with a variable frequency drive for supplying wastewater.
An in-depth calculation of the operation of FLYGT pumping equipment (Sweden) paired with a variable-frequency drive was carried out, thanks to which it was possible to achieve the greatest efficiency and, as a consequence, the lowest cost of pumping wastewater. At the same time, the reliable design of the FLYGT submersible pump has reduced the number of sudden equipment stops due to hydraulic clogging and reduced operating costs in general;
— four submersible mixers Wilo — EMUTR 221.57 — 4/12 (Germany) with a propeller diameter of 2100 mm for mixing activated sludge in the anaerobic and anoxic zones;
— sludge mixture recycling pump from the aerobic zone to the anaerobic zone Wilo — EMU 80-1.30-4/30 S-20-4 (Germany) with a capacity of 5000 m3/hour with a frequency-controlled converter.
The cost of the project is 50 million rubles, the source of funding is the city budget.
In 2011, three primary settling tanks were reconstructed with the replacement of sludge scrapers with IRPO-40 manufactured by NPF Ecoton CJSC (Belgorod). To remove the resulting raw sludge, FLYGT pumps (Sweden) with a capacity of 250 m3/hour with frequency converters are installed. Self-cleaning hydraulics FLYGT (Sweden) made it possible to achieve uninterrupted operation in this area. The volume of budget funds amounted to 43 million rubles.
In 2012, the activated sludge pumping station was reconstructed, where previously there were five circulation pumps from ABS (Germany) with a power of 132 kW, which had exhausted their service life. They were replaced with energy-saving submersible pumps from Kaiguan ZQ 2010-3 (PRC) with a power of 75 kW, operating in automated mode. The capacity of each pump is 3000 m3/day. There are 1-2 pumps in operation, equipped with a frequency converter, which allows flexible adjustment of the technological process depending on changing conditions and allows for economical use of electricity.
In 2013-2016 The reconstruction of biological treatment facilities (three aeration tanks, six secondary settling tanks with a diameter of 40 m) and the construction of a new blower station were carried out. The reconstruction project was carried out by Ecovodokanal LLC (Lipetsk), the general contractor was SENS Firm CJSC (St. Petersburg) and the Lipetskstroy OJSC trust (Lipetsk).
In 2013, the reconstruction of aeration tank No. 1 and two secondary settling tanks was carried out, for which 66 million rubles were spent. In 2014, aeration tank No. 2 and two secondary settling tanks were modernized, for which 45 million rubles were allocated. In 2016, the reconstruction of aeration tank No. 3 and two secondary settling tanks was carried out at a cost of 107.5 million rubles, as well as the construction of a blower station building at a cost of 50 million rubles. 52 million rubles were spent on blower units.
The capacity of the structures at the end of the reconstruction was 221 thousand m3/day.
Initially, aeration tanks used a traditional activated sludge process, which did not provide deep removal of nutrients. During the reconstruction, the Johannesburg process (JHB) was introduced, which provides for the division of the aeration tank into four functional zones (Fig. 1.):
- The anaerobic zone where biologically bound phosphorus is released. The presence of free oxygen or nitrates is not allowed. Wilo-Emu mixing equipment is installed in these areas.
- Anoxic zones with installed agitators in which nitrate nitrogen is converted into nitrogen gas and organic carbon is oxidized by nitrates.
- Aerobic zones in which ammonium nitrogen is oxidized to form nitrates, and organic carbon is converted into carbon dioxide. These zones are aerated. For this purpose, polymer aerators of the APKV series produced by NPF Ecoton CJSC were installed. Structurally, the APKV aerator consists of two pipes nested inside each other with an air gap between them. The outer fibrous-porous pipe (dispersant) is made of high-density polyethylene (HDPE), applied by pneumatic extrusion. The internal perforated pipe is made of low-density polyethylene (HDPE) or PVC. The gap between them is maintained by transverse ring inserts. To attach the aerators to the aeration lash, polyethylene couplings with internal and external threads are provided at the ends of the aerators.
- A degassing zone in which free oxygen is removed from the activated sludge before it is circulated into the anoxic zone and supplied to secondary settling tanks. In these zones, submersible sludge mixture recirculation pumps with a nominal flow rate of 830 l/s are installed on each aeration tank.
Simultaneously with the reconstruction of the aeration tanks-nitri-denitrifiers, the modernization of six secondary settling tanks was carried out with the installation of stainless steel collection trays and a sludge removal system with adjustable suction pumps of the IRVO-40 brand of JSC NPF Ecoton.
Sludge suckers are a single functional complex of equipment and technological devices. The main equipment includes: a bridge truss, sludge collection pipes with sludge collectors and a drive trolley. The working parts of the sludge intake device are sludge intakes that collect activated sludge from the bottom of the settling tank. The sludge intakes are rigidly fixed to the sludge collection collector (beam) pipe(s), suspended on length-adjustable steel braces and equipped with a rubber skirt made up of individual plates. The central rotation support is made in the form of a bearing rotation unit. A bridge truss serves as access to the central part of the sludge scraper. At the outer end of the farm there is a drive trolley equipped with an electric drive with variable speed control and wheels with polyurethane tread. A four-wheel drive trolley is available as an option. The other end of the bridge truss rests on the platform and the central axis. On top of the bridge truss there is a metal or plastic deck fenced with railings.
Sludge suckers and sludge scrapers are designed for many years of trouble-free operation. In particular, an extremely simple but effective sludge intake system, consisting, in contrast to a four-beam sludge intake, from a single sludge pipe, proved to be very effective. This design has proven to be stable, rigid and reliable in operation. The suckers are designed in such a way that there is no sludge settling on the bottom of the settling tank, since they are equipped with original elastic rubber plates that follow the bottom topography. In addition, the single-beam design allowed the collection of sludge at a lower moisture content. The side and edge cleaners of both sludge suckers and sludge scrapers are well designed and easy to adjust. The drive trolleys have a smooth and even ride, and the electrical part of the drive operates without interruption in a wide variety of temperature conditions.
The highest specific energy consumption for equipment operation falls on blower units. The commissioning of a new air blowing station in 2015 with the installation of energy-saving equipment for saturating activated sludge with oxygen made it possible to significantly reduce energy costs. Four Siemens HVSTC-Go blower units with a capacity of 21,000 m3/hour operate automatically and require minimal maintenance. 2-3 units are in constant operation, 1-2 are in reserve. The blade control system makes it possible to control the air flow, obtaining maximum efficiency with minimum performance. According to preliminary calculations, energy savings for the year will be about 876 thousand kW or 4.4 million rubles.
To control process parameters, meters for wastewater, return activated sludge and air are used.
The aeration tanks are equipped with ultrasonic flow meters of the EKHO-R 02 type (Russia), and the volume of air flow is carried out by flow meters from Endress + Hauser (Germany).
The next step in the reconstruction of the city aeration station is the modernization of sludge treatment and disposal facilities, the cost of which is estimated at 250 million rubles. In 2014, Ecovodokanal LLC (Lipetsk) completed design and estimate documentation for Ecovodokanal LLC (Lipetsk). The issue of financing the project, which is planned to be implemented in the next two to three years, is currently being considered.
At a meeting in the city administration, they discussed the modernization of the Lipetsk aeration station - the construction of a new sludge dewatering workshop on the territory of the LiSA municipal unitary enterprise. The meeting was attended by the heads of the regional department of Rosprirodnadzor and the Novolipetsk plant. The project, if implemented, will help reduce the load on the old dewatering complex and use sludge for the production of mineral-organic fertilizer.
NLMK's experience in implementing large-scale environmental programs is interesting and useful for the city. We would like to join forces and synchronize our actions in this area,” said the head of Lipetsk, Sergei Ivanov.
The complex of urban treatment facilities has two technological lines: the first is owned by NLMK PJSC (it also purifies wastewater from the left bank of Lipetsk), the second is municipal (serves the Right Bank). MUP "LiSA" processes the sludge from both lines. According to the director of the enterprise, Evgeny Lisakonov, the total annual volume is 70 thousand tons of dewatered sludge, including about 10 thousand tons from the plant and the Left Bank.
Activated sludge is a colony of special bacteria and protozoa that participate in wastewater treatment. It must be regularly removed from the water treatment process and disposed of. Now this is being done by a specialized organization at a country training ground.
A joint environmental project between the city and NLMK will make it possible to dewater sludge in the new workshop, and then carry out thermophilic anaerobic treatment, which should rid the LTZ area of the unpleasant odor. The processed sludge will not accumulate, but will become a raw material for the production of agricultural fertilizers.
This event of the municipal unitary enterprise "LiSA" is part of a comprehensive plan to reduce emissions of pollutants into the air of Lipetsk, which is being implemented as part of the national project "Clean Air". Representatives of NLMK plan to participate in it as experts.
According to NLMK Group Environmental Director Galina Khristoforova, despite the plant having a reserve landfill for storing sludge, which is not yet in use, we must now think about new solutions that in the future will help reduce the environmental load on the territory. The idea of a joint solution to the problem is supported by the department of Rosprirodnadzor for the Lipetsk region.
We need a balance and a roadmap; we will ask the plant’s specialists to act as experts on the project taken as a basis by the city,” summed up the head of Lipetsk, Sergei Ivanov.
The meeting also discussed the feasibility of building post-treatment systems that will raise the quality of wastewater into the Voronezh River to a new level. The parties agreed on a new meeting and exchange of experience after NLMK representatives studied the options proposed by MUP "LiSA" for the disposal of sludge sludge.
The problem of the quality of wastewater treatment entering the Voronezh River (flowing through three regions of the Central Chernobyl Region) is topical and vitally important. Is there any cause for concern here? We visited the Lipetsk aeration station to find out first-hand how work is organized here, what tasks are currently the most pressing and how they are being solved.
The conversation with the director of the Lipetsk Aeration Station municipal unitary enterprise Evgeny Lisakonov somehow naturally began about the labor collective. We learned with interest that the best traditions of trade union work have been preserved here - a number of social programs are being implemented in the interests of the enterprise's employees.
Evgeniy Nikolaevich, there is no doubt that the most valuable resource of an enterprise is its employees. What working conditions are created for them? Are there any vacancies?
On February 14, at the general meeting of the labor collective, they discussed the pressing problems of the enterprise, consulted, and decided - this is a common practice. This collegiality brings people together; there is a feeling that together everyone is one family. “LiSA” is not only a technological enterprise, but also a socially oriented enterprise, where the trade union committee actively works, our employees are confident and know that their rights and interests are protected and ensured. Our wages are one of the highest among municipal enterprises, and with a total workforce of almost 200 people, there is virtually no turnover. There are no available vacancies, there are many employees who have been working for more than two or three decades, more than a dozen labor dynasties have formed - people are attracted by the reliability and stability of the enterprise. There is a wellness center - with a swimming pool, steam room, showers, and there is also a gym and tennis room. There is a canteen with very affordable prices and transport for delivery to work is provided. This year we rented 2 swimming lanes in sports complexes“Flame” and “Leader” (on Stakhanov Street) so that our employees can use them at a convenient time.
According to the collective agreement, the enterprise compensates employees for part of the costs of paid medical services. We encourage the best, help people in difficult life situations. We try to provide our employees with decent working and rest conditions, and people appreciate this. When we had a break in the on-site water supply networks on February 23, even employees from the rest shift arrived to eliminate the accident. We dealt with the accident entirely on our own - the enterprise has all the necessary materials in case of an emergency. The company has a high social standard and the same requirements for employees, for whom professionalism and responsibility for the results of their work come first. These qualities ensure effective work.
Seven years ago, the company entered into a loan agreement with the European Bank for Reconstruction and Development for a project for the reconstruction of wastewater treatment facilities. What has been done during this time, have sanctions had an impact?
The bank fulfilled all conditions; the amount of the investment loan amounted to 311 million rubles. The funds were used for the reconstruction of 3 aeration tanks, six secondary settling tanks and the construction of a new blower station. After completion of the reconstruction project, all regulatory indicators for the discharge of treated wastewater into the Voronezh River were significantly improved. We are now repaying the loan (80 million rubles annually), its repayment period is the 1st quarter of 2021. For known reasons, the bank has suspended lending in Russia for now, but subsequently, after the loan is repaid, we look forward to further cooperation. In addition, there are guarantees from the city and regional administrations. I am confident that we will complete our credit history correctly and will carefully fulfill our obligations to repay the loan funds. When the loan expires, the released funds will be used for the development and reconstruction of the enterprise.
What is the daily volume of wastewater treated? Does the cleaning level meet accepted standards?
Today, the station is capable of processing about 220 thousand cubic meters of wastewater every day, and approximately 70 thousand cubic meters of sludge are formed per year. Lipetsk is a large industrial center, and heavy metals are present in the sediment, which is a big problem. The implementation of recycling measures is to minimize the removal of sludge with heavy impurities to the landfill and minimize harm to nature.
I’m sure not everyone knows that the requirements for waste water treatment are much stricter than for drinking water. The UES does not have such strict standards, and we need to take into account the deterioration of networks and the capabilities of local budgets. There is a need for amendments to the maximum permissible concentration, making the standard less stringent; this is an important issue at the state level.
- So today there should be no concern about “that” that flows into the Voronezh River?
It can be stated that in terms of the quality of treatment, our waste water is close to drinking water. Purified and ultraviolet disinfected water enters the river. Every step of purification is monitored in our federally accredited laboratory. There is also constant and strict control by Rosprirod and Rospotrebnadzor, the regional environmental department. The measures taken have a beneficial effect on improving the environmental situation. The director of the Galichya Gora Nature Reserve, who recently visited us, was pleased
FOR REFERENCE
The area occupied by the enterprise is 62 hectares. Treatment facilities are a complex complex of structures for mechanical and biological wastewater treatment, disinfection of treated wastewater and sludge treatment.
